A new diketopiperazine heterodimer from an endophytic fungus Aspergillus niger

Abstract

One new diketopiperazine heterodimer, asperazine A (1), and eight known compounds, asperazine (2), cyclo(d-Phe-l-Trp) (3), cyclo(l-Trp-l-Trp) (4), 4-(hydroxymethyl)-5,6-dihydro-pyran-2-one (5), walterolactone A (6), and campyrones A–C (7–9), were isolated from an endophytic fungus Aspergillus niger. Their structures were determined unequivocally on the basis of extensive spectroscopic data analysis. This is the first report of the presence of compound 3 as a natural product. Cytotoxicity test against human cancer cell lines PC3, A2780, K562, MBA-MD-231, and NCI-H1688 revealed that compounds 1 and 2 had weak activities.

Keywords::

• Aspergillus niger
• endophytic fungus
• diketopiperazine heterodimer
• α-pyrone
• cytotoxicity

Acknowledgments

This work was financially supported by the National Natural Science Foundation of China (Nos 81273383, 21272139). We thank Mr Shu-Qi Wang and Mr Bin Ma for the NMR measurements and Mrs Yan-Hui Gao for the HR-ESI-MS determination.